This invention describes two basic design criteria for producing oligonucleotide "negative control probes" for use in nucleic acid hybridization assays. Each type of negative control probe also functions as a synthetic "target" that is useful for testing the other type of negative control probe. These design criteria also provide structures that are not naturally occurring, but are analogous to naturally occurring nucleic acids in primary, secondary and tertiary structure. These design criteria are useful in hybridization assays and potentially in other applications as well.
Examples of embodiments of this invention relate to procedures for detecting and identifying sulfate-reducing bacteria, or SRBs, and more particularly, to the use of oligonucleotide probes complementary to portions of the 16S rRNA molecule of these bacteria to detect and identify sporing and non-sporing sulfate-reducing bacteria and distinguishing them from other bacteria that may also be present in an environmental sample.